<?php

// vim: foldmethod=marker

/* Generic exception class
 */
class doubanOAuthException extends Exception
{
    /*{{{*/
  // pass
}/*}}}*/

class doubanOAuthConsumer
{
    /*{{{*/
  public $key;
    public $secret;

    public function __construct($key, $secret, $callback_url = null)
    {/*{{{*/
    $this->key = $key;
        $this->secret = $secret;
        $this->callback_url = $callback_url;
    }/*}}}*/

  public function __toString()
  {/*{{{*/
    return "OAuthConsumer[key=$this->key,secret=$this->secret]";
  }/*}}}*/
}/*}}}*/

class doubanOAuthToken
{
    /*{{{*/
  // access tokens and request tokens
  public $key;
    public $secret;

  /**
   * key = the token
   * secret = the token secret
   */
  public function __construct($key, $secret)
  {/*{{{*/
    $this->key = $key;
      $this->secret = $secret;
  }/*}}}*/

  /**
   * generates the basic string serialization of a token that a server
   * would respond to request_token and access_token calls with
   */
  public function to_string()
  {/*{{{*/
    return 'oauth_token='.doubanOAuthUtil::urlencode_rfc3986($this->key).
        '&oauth_token_secret='.doubanOAuthUtil::urlencode_rfc3986($this->secret);
  }/*}}}*/

  public function __toString()
  {/*{{{*/
    return $this->to_string();
  }/*}}}*/
}/*}}}*/

class doubanOAuthSignatureMethod
{
    /*{{{*/
  public function check_signature(&$request, $consumer, $token, $signature)
  {
      $built = $this->build_signature($request, $consumer, $token);

      return $built == $signature;
  }
}/*}}}*/

class doubanOAuthSignatureMethod_HMAC_SHA1 extends doubanOAuthSignatureMethod
{
    /*{{{*/
  public function get_name()
  {/*{{{*/
    return 'HMAC-SHA1';
  }/*}}}*/

  public function build_signature($request, $consumer, $token)
  {/*{{{*/
    $base_string = $request->get_signature_base_string();
      $request->base_string = $base_string;

      $key_parts = array(
      $consumer->secret,
      ($token) ? $token->secret : '',
    );

      $key_parts = doubanOAuthUtil::urlencode_rfc3986($key_parts);
      $key = implode('&', $key_parts);

      return base64_encode(hash_hmac('sha1', $base_string, $key, true));
  }/*}}}*/
}/*}}}*/

class doubanOAuthSignatureMethod_PLAINTEXT extends doubanOAuthSignatureMethod
{
    /*{{{*/
  public function get_name()
  {/*{{{*/
    return 'PLAINTEXT';
  }/*}}}*/

  public function build_signature($request, $consumer, $token)
  {/*{{{*/
    $sig = array(
      doubanOAuthUtil::urlencode_rfc3986($consumer->secret),
    );

      if ($token) {
          array_push($sig, doubanOAuthUtil::urlencode_rfc3986($token->secret));
      } else {
          array_push($sig, '');
      }

      $raw = implode('&', $sig);
    // for debug purposes
    $request->base_string = $raw;

      return doubanOAuthUtil::urlencode_rfc3986($raw);
  }/*}}}*/
}/*}}}*/

class doubanOAuthSignatureMethod_RSA_SHA1 extends doubanOAuthSignatureMethod
{
    /*{{{*/
  public function get_name()
  {/*{{{*/
    return 'RSA-SHA1';
  }/*}}}*/

  protected function fetch_public_cert(&$request)
  {/*{{{*/
    // not implemented yet, ideas are:
    // (1) do a lookup in a table of trusted certs keyed off of consumer
    // (2) fetch via http using a url provided by the requester
    // (3) some sort of specific discovery code based on request
    //
    // either way should return a string representation of the certificate
    throw Exception('fetch_public_cert not implemented');
  }/*}}}*/

  protected function fetch_private_cert(&$request)
  {/*{{{*/
    // not implemented yet, ideas are:
    // (1) do a lookup in a table of trusted certs keyed off of consumer
    //
    // either way should return a string representation of the certificate
    throw Exception('fetch_private_cert not implemented');
  }/*}}}*/

  public function build_signature(&$request, $consumer, $token)
  {/*{{{*/
    $base_string = $request->get_signature_base_string();
      $request->base_string = $base_string;

    // Fetch the private key cert based on the request
    $cert = $this->fetch_private_cert($request);

    // Pull the private key ID from the certificate
    $privatekeyid = openssl_get_privatekey($cert);

    // Sign using the key
    $ok = openssl_sign($base_string, $signature, $privatekeyid);

    // Release the key resource
    openssl_free_key($privatekeyid);

      return base64_encode($signature);
  } /*}}}*/

  public function check_signature(&$request, $consumer, $token, $signature)
  {/*{{{*/
    $decoded_sig = base64_decode($signature);

      $base_string = $request->get_signature_base_string();

    // Fetch the public key cert based on the request
    $cert = $this->fetch_public_cert($request);

    // Pull the public key ID from the certificate
    $publickeyid = openssl_get_publickey($cert);

    // Check the computed signature against the one passed in the query
    $ok = openssl_verify($base_string, $decoded_sig, $publickeyid);

    // Release the key resource
    openssl_free_key($publickeyid);

      return $ok == 1;
  } /*}}}*/
}/*}}}*/

class doubanOAuthRequest
{
    /*{{{*/
  private $parameters;
    private $http_method;
    private $http_url;
  // for debug purposes
  public $base_string;
    public static $version = '1.0';

    public function __construct($http_method, $http_url, $parameters = null)
    {/*{{{*/
    @$parameters or $parameters = array();
        $this->parameters = $parameters;
        $this->http_method = $http_method;
        $this->http_url = $http_url;
    }/*}}}*/

  /**
   * attempt to build up a request from what was passed to the server
   */
  public static function from_request($http_method = null, $http_url = null, $parameters = null)
  {/*{{{*/
    $scheme = (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != 'on') ? 'http' : 'https';
      @$http_url or $http_url = $scheme.'://'.$_SERVER['HTTP_HOST'].':'.$_SERVER['SERVER_PORT'].$_SERVER['REQUEST_URI'];
      @$http_method or $http_method = $_SERVER['REQUEST_METHOD'];

      $request_headers = doubanOAuthRequest::get_headers();

    // let the library user override things however they'd like, if they know
    // which parameters to use then go for it, for example XMLRPC might want to
    // do this
    if ($parameters) {
        $req = new doubanOAuthRequest($http_method, $http_url, $parameters);
    } else {
        // collect request parameters from query string (GET) and post-data (POST) if appropriate (note: POST vars have priority)
      $req_parameters = $_GET;
        if ($http_method == 'POST' && @strstr($request_headers['Content-Type'], 'application/x-www-form-urlencoded')) {
            $req_parameters = array_merge($req_parameters, $_POST);
        }

      // next check for the auth header, we need to do some extra stuff
      // if that is the case, namely suck in the parameters from GET or POST
      // so that we can include them in the signature
      if (@substr($request_headers['Authorization'], 0, 6) == 'OAuth ') {
          $header_parameters = doubanOAuthRequest::split_header($request_headers['Authorization']);
          $parameters = array_merge($req_parameters, $header_parameters);
          $req = new doubanOAuthRequest($http_method, $http_url, $parameters);
      } else {
          $req = new doubanOAuthRequest($http_method, $http_url, $req_parameters);
      }
    }

      return $req;
  }/*}}}*/

  /**
   * pretty much a helper function to set up the request
   */
  public static function from_consumer_and_token($consumer, $token, $http_method, $http_url, $parameters = null)
  {/*{{{*/
    @$parameters or $parameters = array();
      $defaults = array('oauth_version' => doubanOAuthRequest::$version,
                      'oauth_nonce' => doubanOAuthRequest::generate_nonce(),
                      'oauth_timestamp' => doubanOAuthRequest::generate_timestamp(),
                      'oauth_consumer_key' => $consumer->key, );
      $parameters = array_merge($defaults, $parameters);

      if ($token) {
          $parameters['oauth_token'] = $token->key;
      }

      return new doubanOAuthRequest($http_method, $http_url, $parameters);
  }/*}}}*/

  public function set_parameter($name, $value)
  {/*{{{*/
    $this->parameters[$name] = $value;
  }/*}}}*/

  public function get_parameter($name)
  {/*{{{*/
    return isset($this->parameters[$name]) ? $this->parameters[$name] : null;
  }/*}}}*/

  public function get_parameters()
  {/*{{{*/
    return $this->parameters;
  }/*}}}*/

  /**
   * Returns the normalized parameters of the request
   *
   * This will be all (except oauth_signature) parameters,
   * sorted first by key, and if duplicate keys, then by
   * value.
   *
   * The returned string will be all the key=value pairs
   * concated by &.
   *
   * @return string
   */
  public function get_signable_parameters()
  {/*{{{*/
    // Grab all parameters
    $params = $this->parameters;

    // Remove oauth_signature if present
    if (isset($params['oauth_signature'])) {
        unset($params['oauth_signature']);
    }

    // Urlencode both keys and values
    $keys = doubanOAuthUtil::urlencode_rfc3986(array_keys($params));
      $values = doubanOAuthUtil::urlencode_rfc3986(array_values($params));
      $params = array_combine($keys, $values);

    // Sort by keys (natsort)
    uksort($params, 'strcmp');

    // Generate key=value pairs
    $pairs = array();
      foreach ($params as $key => $value) {
          if (is_array($value)) {
              // If the value is an array, it's because there are multiple
        // with the same key, sort them, then add all the pairs
        natsort($value);
              foreach ($value as $v2) {
                  $pairs[] = $key.'='.$v2;
              }
          } else {
              $pairs[] = $key.'='.$value;
          }
      }

    // Return the pairs, concated with &
    return implode('&', $pairs);
  }/*}}}*/

  /**
   * Returns the base string of this request
   *
   * The base string defined as the method, the url
   * and the parameters (normalized), each urlencoded
   * and the concated with &.
   */
  public function get_signature_base_string()
  {/*{{{*/
    $parts = array(
      $this->get_normalized_http_method(),
      $this->get_normalized_http_url(),
      $this->get_signable_parameters(),
    );

      $parts = doubanOAuthUtil::urlencode_rfc3986($parts);

      return implode('&', $parts);
  }/*}}}*/

  /**
   * just uppercases the http method
   */
  public function get_normalized_http_method()
  {/*{{{*/
    return strtoupper($this->http_method);
  }/*}}}*/

  /**
   * parses the url and rebuilds it to be
   * scheme://host/path
   */
  public function get_normalized_http_url()
  {/*{{{*/
    $parts = parse_url($this->http_url);

      $port = @$parts['port'];
      $scheme = $parts['scheme'];
      $host = $parts['host'];
      $path = @$parts['path'];

      $port or $port = ($scheme == 'https') ? '443' : '80';

      if (($scheme == 'https' && $port != '443')
        || ($scheme == 'http' && $port != '80')) {
          $host = "$host:$port";
      }

      return "$scheme://$host$path";
  }/*}}}*/

  /**
   * builds a url usable for a GET request
   */
  public function to_url()
  {/*{{{*/
    $out = $this->get_normalized_http_url().'?';
      $out .= $this->to_postdata();

      return $out;
  }/*}}}*/

  /**
   * builds the data one would send in a POST request
   *
   * TODO(morten.fangel):
   * this function might be easily replaced with http_build_query()
   * and corrections for rfc3986 compatibility.. but not sure
   */
  public function to_postdata()
  {/*{{{*/
    $total = array();
      foreach ($this->parameters as $k => $v) {
          if (is_array($v)) {
              foreach ($v as $va) {
                  $total[] = doubanOAuthUtil::urlencode_rfc3986($k).'[]='.doubanOAuthUtil::urlencode_rfc3986($va);
              }
          } else {
              $total[] = doubanOAuthUtil::urlencode_rfc3986($k).'='.doubanOAuthUtil::urlencode_rfc3986($v);
          }
      }
      $out = implode('&', $total);

      return $out;
  }/*}}}*/

  /**
   * builds the Authorization: header
   */
  public function to_header()
  {/*{{{*/
    $out = 'Authorization: OAuth realm=""';
      $total = array();
      foreach ($this->parameters as $k => $v) {
          if (substr($k, 0, 5) != 'oauth') {
              continue;
          }
          if (is_array($v)) {
              throw new doubanOAuthException('Arrays not supported in headers');
          }
          $out .= ','.doubanOAuthUtil::urlencode_rfc3986($k).'="'.doubanOAuthUtil::urlencode_rfc3986($v).'"';
      }

      return $out;
  }/*}}}*/

  public function __toString()
  {/*{{{*/
    return $this->to_url();
  }/*}}}*/

  public function sign_request($signature_method, $consumer, $token)
  {/*{{{*/
    $this->set_parameter('oauth_signature_method', $signature_method->get_name());
      $signature = $this->build_signature($signature_method, $consumer, $token);
      $this->set_parameter('oauth_signature', $signature);
  }/*}}}*/

  public function build_signature($signature_method, $consumer, $token)
  {/*{{{*/
    $signature = $signature_method->build_signature($this, $consumer, $token);

      return $signature;
  }/*}}}*/

  /**
   * util function: current timestamp
   */
  private static function generate_timestamp()
  {/*{{{*/
    return time();
  }/*}}}*/

  /**
   * util function: current nonce
   */
  private static function generate_nonce()
  {/*{{{*/
    $mt = microtime();
      $rand = mt_rand();

      return md5($mt.$rand); // md5s look nicer than numbers
  }/*}}}*/

  /**
   * util function for turning the Authorization: header into
   * parameters, has to do some unescaping
   */
  private static function split_header($header)
  {/*{{{*/
    $pattern = '/(([-_a-z]*)=("([^"]*)"|([^,]*)),?)/';
      $offset = 0;
      $params = array();
      while (preg_match($pattern, $header, $matches, PREG_OFFSET_CAPTURE, $offset) > 0) {
          $match = $matches[0];
          $header_name = $matches[2][0];
          $header_content = (isset($matches[5])) ? $matches[5][0] : $matches[4][0];
          $params[$header_name] = doubanOAuthUtil::urldecode_rfc3986($header_content);
          $offset = $match[1] + strlen($match[0]);
      }

      if (isset($params['realm'])) {
          unset($params['realm']);
      }

      return $params;
  }/*}}}*/

  /**
   * helper to try to sort out headers for people who aren't running apache
   */
  private static function get_headers()
  {/*{{{*/
    if (function_exists('apache_request_headers')) {
        // we need this to get the actual Authorization: header
      // because apache tends to tell us it doesn't exist
      return apache_request_headers();
    }
    // otherwise we don't have apache and are just going to have to hope
    // that $_SERVER actually contains what we need
    $out = array();
      foreach ($_SERVER as $key => $value) {
          if (substr($key, 0, 5) == 'HTTP_') {
              // this is chaos, basically it is just there to capitalize the first
        // letter of every word that is not an initial HTTP and strip HTTP
        // code from przemek
        $key = str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($key, 5)))));
              $out[$key] = $value;
          }
      }

      return $out;
  }/*}}}*/
}/*}}}*/

class doubanOAuthServer
{
    /*{{{*/
  protected $timestamp_threshold = 300; // in seconds, five minutes
  protected $version = 1.0;             // hi blaine
  protected $signature_methods = array();

    protected $data_store;

    public function __construct($data_store)
    {/*{{{*/
    $this->data_store = $data_store;
    }/*}}}*/

  public function add_signature_method($signature_method)
  {/*{{{*/
    $this->signature_methods[$signature_method->get_name()] =
        $signature_method;
  }/*}}}*/

  // high level functions

  /**
   * process a request_token request
   * returns the request token on success
   */
  public function fetch_request_token(&$request)
  {/*{{{*/
    $this->get_version($request);

      $consumer = $this->get_consumer($request);

    // no token required for the initial token request
    $token = null;

      $this->check_signature($request, $consumer, $token);

      $new_token = $this->data_store->new_request_token($consumer);

      return $new_token;
  }/*}}}*/

  /**
   * process an access_token request
   * returns the access token on success
   */
  public function fetch_access_token(&$request)
  {/*{{{*/
    $this->get_version($request);

      $consumer = $this->get_consumer($request);

    // requires authorized request token
    $token = $this->get_token($request, $consumer, 'request');

      $this->check_signature($request, $consumer, $token);

      $new_token = $this->data_store->new_access_token($token, $consumer);

      return $new_token;
  }/*}}}*/

  /**
   * verify an api call, checks all the parameters
   */
  public function verify_request(&$request)
  {/*{{{*/
    $this->get_version($request);
      $consumer = $this->get_consumer($request);
      $token = $this->get_token($request, $consumer, 'access');
      $this->check_signature($request, $consumer, $token);

      return array($consumer, $token);
  }/*}}}*/

  // Internals from here
  /**
   * version 1
   */
  private function get_version(&$request)
  {/*{{{*/
    $version = $request->get_parameter('oauth_version');
      if (!$version) {
          $version = 1.0;
      }
      if ($version && $version != $this->version) {
          throw new doubanOAuthException("OAuth version '$version' not supported");
      }

      return $version;
  }/*}}}*/

  /**
   * figure out the signature with some defaults
   */
  private function get_signature_method(&$request)
  {/*{{{*/
    $signature_method =
        @$request->get_parameter('oauth_signature_method');
      if (!$signature_method) {
          $signature_method = 'PLAINTEXT';
      }
      if (!in_array($signature_method,
                  array_keys($this->signature_methods))) {
          throw new doubanOAuthException(
        "Signature method '$signature_method' not supported try one of the following: ".implode(', ', array_keys($this->signature_methods))
      );
      }

      return $this->signature_methods[$signature_method];
  }/*}}}*/

  /**
   * try to find the consumer for the provided request's consumer key
   */
  private function get_consumer(&$request)
  {/*{{{*/
    $consumer_key = @$request->get_parameter('oauth_consumer_key');
      if (!$consumer_key) {
          throw new doubanOAuthException('Invalid consumer key');
      }

      $consumer = $this->data_store->lookup_consumer($consumer_key);
      if (!$consumer) {
          throw new doubanOAuthException('Invalid consumer');
      }

      return $consumer;
  }/*}}}*/

  /**
   * try to find the token for the provided request's token key
   */
  private function get_token(&$request, $consumer, $token_type = 'access')
  {/*{{{*/
    $token_field = @$request->get_parameter('oauth_token');
      $token = $this->data_store->lookup_token(
      $consumer, $token_type, $token_field
    );
      if (!$token) {
          throw new doubanOAuthException("Invalid $token_type token: $token_field");
      }

      return $token;
  }/*}}}*/

  /**
   * all-in-one function to check the signature on a request
   * should guess the signature method appropriately
   */
  private function check_signature(&$request, $consumer, $token)
  {/*{{{*/
    // this should probably be in a different method
    $timestamp = @$request->get_parameter('oauth_timestamp');
      $nonce = @$request->get_parameter('oauth_nonce');

      $this->check_timestamp($timestamp);
      $this->check_nonce($consumer, $token, $nonce, $timestamp);

      $signature_method = $this->get_signature_method($request);

      $signature = $request->get_parameter('oauth_signature');
      $valid_sig = $signature_method->check_signature(
      $request,
      $consumer,
      $token,
      $signature
    );

      if (!$valid_sig) {
          throw new doubanOAuthException('Invalid signature');
      }
  }/*}}}*/

  /**
   * check that the timestamp is new enough
   */
  private function check_timestamp($timestamp)
  {/*{{{*/
    // verify that timestamp is recentish
    $now = time();
      if ($now - $timestamp > $this->timestamp_threshold) {
          throw new doubanOAuthException("Expired timestamp, yours $timestamp, ours $now");
      }
  }/*}}}*/

  /**
   * check that the nonce is not repeated
   */
  private function check_nonce($consumer, $token, $nonce, $timestamp)
  {/*{{{*/
    // verify that the nonce is uniqueish
    $found = $this->data_store->lookup_nonce($consumer, $token, $nonce, $timestamp);
      if ($found) {
          throw new doubanOAuthException("Nonce already used: $nonce");
      }
  }/*}}}*/
}/*}}}*/

class doubanOAuthDataStore
{
    /*{{{*/
  public function lookup_consumer($consumer_key)
  {/*{{{*/
    // implement me
  }/*}}}*/

  public function lookup_token($consumer, $token_type, $token)
  {/*{{{*/
    // implement me
  }/*}}}*/

  public function lookup_nonce($consumer, $token, $nonce, $timestamp)
  {/*{{{*/
    // implement me
  }/*}}}*/

  public function new_request_token($consumer)
  {/*{{{*/
    // return a new token attached to this consumer
  }/*}}}*/

  public function new_access_token($token, $consumer)
  {/*{{{*/
    // return a new access token attached to this consumer
    // for the user associated with this token if the request token
    // is authorized
    // should also invalidate the request token
  }/*}}}*/
}/*}}}*/

/*  A very naive dbm-based oauth storage
 */
class SimpleOAuthDataStore extends doubanOAuthDataStore
{
    /*{{{*/
  private $dbh;

    public function __construct($path = 'oauth.gdbm')
    {/*{{{*/
    $this->dbh = dba_popen($path, 'c', 'gdbm');
    }/*}}}*/

  public function __destruct()
  {/*{{{*/
    dba_close($this->dbh);
  }/*}}}*/

  public function lookup_consumer($consumer_key)
  {/*{{{*/
    $rv = dba_fetch("consumer_$consumer_key", $this->dbh);
      if ($rv === false) {
          return null;
      }
      $obj = unserialize($rv);
      if (!($obj instanceof doubanOAuthConsumer)) {
          return null;
      }

      return $obj;
  }/*}}}*/

  public function lookup_token($consumer, $token_type, $token)
  {/*{{{*/
    $rv = dba_fetch("${token_type}_${token}", $this->dbh);
      if ($rv === false) {
          return null;
      }
      $obj = unserialize($rv);
      if (!($obj instanceof doubanOAuthToken)) {
          return null;
      }

      return $obj;
  }/*}}}*/

  public function lookup_nonce($consumer, $token, $nonce, $timestamp)
  {/*{{{*/
    if (dba_exists("nonce_$nonce", $this->dbh)) {
        return true;
    } else {
        dba_insert("nonce_$nonce", '1', $this->dbh);

        return false;
    }
  }/*}}}*/

  public function new_token($consumer, $type = 'request')
  {/*{{{*/
    $key = md5(time());
      $secret = time() + time();
      $token = new doubanOAuthToken($key, md5(md5($secret)));
      if (!dba_insert("${type}_$key", serialize($token), $this->dbh)) {
          throw new doubanOAuthException('doooom!');
      }

      return $token;
  }/*}}}*/

  public function new_request_token($consumer)
  {/*{{{*/
    return $this->new_token($consumer, 'request');
  }/*}}}*/

  public function new_access_token($token, $consumer)
  {/*{{{*/

    $token = $this->new_token($consumer, 'access');
      dba_delete('request_'.$token->key, $this->dbh);

      return $token;
  }/*}}}*/
}/*}}}*/

class doubanOAuthUtil
{
    /*{{{*/
  public static function urlencode_rfc3986($input)
  {/*{{{*/
  if (is_array($input)) {
      return array_map(array('doubanOAuthUtil', 'urlencode_rfc3986'), $input);
  } elseif (is_scalar($input)) {
      return str_replace('+', ' ',
                         str_replace('%7E', '~', rawurlencode($input)));
  } else {
      return '';
  }
  }/*}}}*/

  // This decode function isn't taking into consideration the above
  // modifications to the encoding process. However, this method doesn't
  // seem to be used anywhere so leaving it as is.
  public static function urldecode_rfc3986($string)
  {/*{{{*/
    return rawurldecode($string);
  }/*}}}*/
}/*}}}*/
